Rotary piston engine



Jan. 17, 1967 RYUSUKE lTo ETAL 3,298,330

ROTARY PISTON ENGINE Filed April l, 1965 Hiroshi Facia Sei-0 Immo ATTORNEYS By 1M MW, mv ff/m United States Patent() 3,298,330 ROTARY PISTON ENGINE Ryusuke Ito, Amagasaki-shi, Hiroshi Tado, Suita-shi, and

Seizo Jinno, Nagahama-shi, Japan, assignors to Yanmar Diesel Engine Co., Ltd., Osaka, Japan Filed Apr. 1, 1965, Ser. No. 444,706 Claims priority, application Japan, Apr. 22, 1964, E39/22,416 1 Claim. (Cl. 123-8) This invention relates to a rotary piston engine and, more particularly, to a rotary piston engine of the type having a casing which includes a center housing having an inner sliding surface contoured in a -multinodal epitrochoid with opposite side housings attached thereto, and a rotor having a plurality of apices and mounted in said casing for eccentric rotation therein.

In this type of rotary piston engine an area ofthe center housing corresponding to the suction stroke is kept at a low temperature, because it is always cooled by gaseous mixture (this area will be hereinafter called cooled arc area), while another area corresponding to the explosion stroke is kept at a high temperature because it is always exposed to combustion gas (this area will be hereinafter called heated `arc area). The deformation of the center housing caused by the difference of temperature gives bad influence on the wear of the sliding surface of this center housing. For the reason it is `desirable to minimize the temperature difference in the center housing by lowering the temperature of the heated arc area and raising the temperature of the cooled arc area.

Further, in this type of rotary piston engine a method of circulating a cooling medium (hereinafter called lubricant because, in general, lubricant is used) through the rotor is employed to absorb the heat which has been given to the rotor by the combustion gas through the wall of the combustion chamber and thereby to keep the temperature of the rotor moderate. Accordingly, the lubricant must be cooled.

This invention provides a rotary piston engine which meets above stated two conditions. The rotary piston engine of this invention is designed so that the cooled arc areas of the center housing and side housings are heated by lubricant which passes through passages in the cooled arc areas of the center housing and side housings. Since the lubricant can be cooled in this process, it enables one to spare a lubricant cooling means which is mostly set up outside the engine body, or to make the capacity of the cooling means smaller.

Additionally, this system brings about another effect, that is, in heating of the cooled arc areas the gaseous mixture which has been sucked in is also heated, which improves the combustion eiiiciency lof the gaseous mixture.

Now the invention will be described with reference to the drawings.

FIG. l is a transverse cross sectional view of the central portions of the center housing and side housings of a rotary piston engine embodying the present invention;

FIG. 2 is an explanatory view showing the cooling water circuit and lubricant cir-cuit of the central housing and side housings embodying the present invention; and

FIG. 3 is a diagram showing the cooling Water circuit and lubricant circuit in the cooling system according to the present invention.

In FIG. l a space 3 dened by an inner Wall 6 and an outer wall 7 in the center housing 1 is divided into two parts A and B by partition walls 5 and 9; A serves as a passage -for cooling water and B as a passage for lubricant. Similarly a space in each of the side housings is divided into two parts C and D by a partition wall 12; C serves as a passage for cooling water and D as a passage for lubricant. In each lubricant passage D, guide ribs 13 are arranged to make the lubricant ilow uniformly in the cooled arc area and at the same time to work as lubricant cooling tins. If necessary, guide ribs can be arranged also in the cooling water passage C to promote cooling and uniform flow of cooling water.

The larger part of the cooling Water which enters into the center housing from a cooling water inlet port 2 passes through the cooling Water passage A of the center housing cooling the inner Wall 6 of the heated arc area, and is dis-l charged from a cooling Water exhaust port 11.

The remaining cooling water flows into the side housings 13 and 14 through cooling water pass 10, passes through the cooling water passages C of the side housings cooling the sliding walls of the side housings, enters again into the center housing through another cooling Water pass 15 and is exhausted from the cooling water exhaust port 11.

Next, the lubricant circuit will be described. The lubricant flows into one side housing 13 from an inlet 20, passes through the lubricant passage D beating the sliding Wall of the cooled arc area, enters into the lubricant passage B of the center housing through lubricant passes 21 and 21, heats the inner wall 6 of the cooled arc area, moves into the other side housing 14 through lubricant passes 22 and 22', passes through the lubricant passage D heating the sliding wall of the cooled arc area, and is discharged from a lubricant exhaust port 23. The lubricant after being cooled 'by the lubricant cooling means is supplied to the inside 4 of the rotor 24 through lan oil hole 16 of an eccentric shaft 5 and a rotor oil hole 18, cools the inner surfaces o-f the combustion chamber and is exhausted through one of the side housings.

FIGS. 2 and 3 illustrate the cooling water and lubricant circuits.

The rotary piston engine of this invention having such a structure as has been-described above, by heating the sliding walls of the cooled a-rc areas reduces the temperature difference between the cooled arc areas and the heated arc areas to minimize the thermal deformation of the center housing and side housings, at the same time to preheat the gaseous mixture which has been sucked in and thereby to increase combustion efliciency thereof, and to give good effects on cooling of the lubricant. In other embodiments of this invention whe-re lubricant is cooled in other methods than that of this embodiment, it is possible to make use -of a part of cooling Water which, after finishing cooling of the heated arc areas, has been further heated by exhaust gaseous mixture and the like to heat the cooled arc areas instead of lubricant.

What is claimed is:

A rotary piston engine comprising a center housing and a side housing positioned on each side of said center housing; said center housing comprising an inner wall and an outer wall together defining a substantially annular space therebetween, and a iirst pair of partition Walls dividing said annular space into a rst cooling water passage and a first lubricant passage; each of said side housings 3 l 4 comprising a second pair of partition walls dividing each 3,007,460 11/ 1961 Bentele et al 123-8 of said side housings into a second cooling water passage 3,012,550 12/1961 paschke 123 g and a second lubricant passage; said rst cooling water 3 042 009 7/1962 Froede et al 123 8 passage communicating with each of said second cooling Water passages, and said first lubricant passage com- 5 3,091,386 5/1963 Pschke 23o-145 municating with each of said second lubricant passages. 3,102,516 9/ 1963 GlSt et al. 123-8 3,134,537 5/1964 Bentele et al 230-210 References Cited by the Examiner UNITED STATES PATENTS DONLEY I. STOCKING, Primary Examiner.

2,988,065 6/1961 wankeletal.; 23o-210 10 W- J- GOODLIN, Assistant Examiner. 

